After publishing novels more than thirty years, I’ve grown accustomed to all sorts of letters and emails from my readers. The most interesting and unusual one I ever received came last week from a 65-year-old woman living in the Midwest. It was in response to my latest novel, Creole Son, about French painter Edgar Degas’s 1872-3 visit to New Orleans and his encounter with an exotic caste classification based on degree of skin color. For those who didn’t read the book or are unfamiliar with the system, an octoroon is a person who is one eighth black and seven eighths white. Below is an old lithograph of a mulatto (left) and a quadroon, a person one quarter black, three quarters white. I was given permission to publish the following letter on the...